Microplastic Accumulation in Deep-Sea and Surface Sediments on the GEOTRACE Med Black Sea Cruise: Composition, Distribution, and Polymer Characterization

The pollution caused by microplastics (MPs) in marine sediments has been a concern of many researchers thanks to these substances’ persistence and potential ecological effects. To our knowledge, this study represents the first comprehensive investigation of MP contamination in marine sediments collected from multiple regions of the Mediterranean Sea, encompassing a wide bathymetric range from coastal areas to deep-sea environments, down to approximately 4000 m water depth. Sediment samples were taken from several sites in the Mediterranean and the northern Aegean Sea. Thanks to microscopic analysis, fragments and filaments were the dominant MP forms; their color and size varied, and the most frequent particle colors were red, transparent and blue. FTIR spectroscopy revealed diverse types of polymers, including polystyrene (PS), propylene (PP), ethylene–vinylacetate (EVA), polyamide (PA), and Acrylonitrile Butadiene Styrene (ABS) polymer. The 1-H NMR analyses confirmed the presence of PA, EVA, PP, polyethylene (PE), and PS, thereby supporting the FTIR results. This spatial variability in polymer composition probably reflects both regional anthropogenic inputs and hydrodynamic factors affecting sedimentary deposits. These results detail the complex and generalized nature of MP contamination in Mediterranean sediments and offer a basis from which to start assessing ecological risks and developing targeted mitigation strategies.